Rating of Underground Power Cables With Boundary Temperature Restrictions

This paper discusses rating calculations of underground power cables when the temperature limit is imposed on a location other than the cable conductor. The issue becomes important for installations where the environmental conditions do not allow excessive heating. An example can be a requirement that the cable surface temperature is such that the drying out of the surrounding soil is avoided. Another example is a requirement imposed on submarine cable installations when the temperature rise caused by cable heating at the specified depth below the sea bottom does not exceed 2 K. Such requirements form rating restrictions in several countries; for example, the Netherlands, Germany, France, and others. This paper proposes new solutions to such problems including calculation of the dynamic ratings.